2012/5/28 Bryce Johnson <sie...@gmail.com>: > I've just been trying to tune my gantry setup and I have had a few > problems. I am using 2.5. > > I am using gantrykins with XYZX. I am trying to set up my limits for for > speed on my Z axis of 180ipm. In joint mode, jogging around, it seems to > obey this. When I switch to world it doesn't listen to that limit anymore > and I can (try to) jog it up to my MAX_LINEAR_VELOCITY = 6.00 in my > [TRAJ] in my ini. This will throw a joint error. >
I guess "joint following error" is meant here. > > It seems like I lose some flexibility when using gantrykins vs just slaving > the drives together (although I would like to be able to home both X1 and > X2 independently). Is there a way to home the drives and then run it as if > they were slaved? > If I understand correctly, then You are having difficulties with Z axis, but gantrykins simply maps 2 joints to X axis, so I do not see, how changing kinematics module (and hardwire slaving the 2nd joint) will help here. My suggestion (could be considered as workaround) is: in [TRAJ] section 1) set default_linear_velocity to something that Your Z axis can handle 2) set max_linear_velocity to something that Your X and Y can handle when You need to jog Z, simply jog it at default speed. When You want to jog X or Y at max speed, press "shift" and arrows - it will jog at max velocity. I am not sure, how that all really works, but explicitly telling LinuxCNC to jog a joint faster than it is capable to do so is something it will complain about. I guess that simply limiting that speed to joint's max velocity would be better, but I assume there may be a reason for not to be set up this way, I really do not know. > > > And then some other problems are my somewhat poor base period (this is the > reason my Z can't go about about 180ipm on a screw drive). I have a > 3 GHz pentium 4. Tried the SMI fix, an external video card,and disabling > all the power saving stuff in the bios and can't seem to get it below > ~45000 jitter worst case. I've thought about getting one of those little > atom boards to improve the stepping, or should I get one of those mesa > cards I keep seeing you guys use (like 5i25? at $90 that would be as cheap > as a atom board). Could I plug that directly into my C10 breakout board > from keling (http://www.kelinginc.com/c10.pdf)? > 45000 is really unpleasant. Is that single-core or dual-core cpu? I am typing this on dual-core Pentium - I do not know, when did Intel manage to put those out, I thought they were calling all dual-core cpus to be " core2duo" or something like that until I got this PC. FPGA cards available for LinuxCNC will connect directly to PC either via LPT port (Pico Systems cards and Mesa's 7i43) or in pci slot (Mesa's 5i23, 5i25 etc). FPGA cards will not plug in any breakout board of whatsoever. If You want to use Your existing Keling breakout board, I would suggest 5i25. Take the pinout of that board and check with Mesa people, if it matches with any of existing firmwares (there should be a match, but AFAIK they will adjust one for You, if there isn't). So in the end You should be able to plug the lpt cable from Your breakout board in 5i25 and just tweak Your config a little bit. Cost-wise it would be the same as atom board, but performance-wise use of FPGA card beats any software-stepping setup in many points, including smoother step signals, increased number of i/o pins, better realtime performance etc. -- Viesturs If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
